A number of research, diagnostic and analytical techniques involve the use of monoclonal antibodies. These are homogeneous antibody preparations derived from hybridoma cell cultures. Unfortunately, a number of monoclonal antibody preparations are thermally unstable. This is a distinct disadvantage, since transportation and storage impose considerable thermal stress upon the antibody preparation.
Because of this disadvantage, many current applications for antibodies use polyclonal antibodies, i.e., antibodies produced by cells containing a variety of cell lines, as are obtained from animals, which naturally and spontaneously produce antibodies in polyclonal form. However, while these polyclonal antibodies offer better thermal stability, they have the disadvantage of limited specificity and are cross-reactive to antigens related to their intended antigen. This limits the accuracy and reliability of tests in which the polyclonal antibodies are used. For example, a polyclonal antibody specific for the therapeutic agents theophylline or aminophylline can exhibit cross-reactivity to other common xanthines, such as caffeine and theobromine. A patient whose blood theophylline level is being followed by immunoassay must abstain from coffee, tea, colas, cocoa, and similar materials, or risk producing a false high result in the assay. An immunoassay using a stable and more specific monoclonal antibody could minimize this problem. Thus, an art-recognized need exists for a method of stabilizing monoclonal antibody preparations against thermal damage, and for thermally stable monoclonal antibody compositions.